Optical plate having three layers and backlight module with same

Abstract

An exemplary optical plate includes a first transparent layer, a second transparent layer and a light diffusion layer between the first and second transparent layers. The above-described three layers are integrally formed, with the first transparent layer in immediate contact with the light diffusion layer, and the second transparent layer in immediate contact with the light diffusion layer. The first transparent layer defines micro depressions protruding from an outer surface thereof. Each micro depression has at least three side surfaces connected to each other, and a transverse width of each side surface increases along a direction away from the light diffusion layer. The second transparent layer defines conical frustum protrusions at an outer surface thereof.

1 . An optical plate, comprising:
 a first transparent layer;   a second transparent layer; and   a light diffusion layer between the first transparent layer and the second transparent layer, the light diffusion layer including a transparent matrix resin and a plurality of diffusion particles dispersed in the transparent matrix resin, wherein the light diffusion layer, the first transparent layer, and the second transparent layer are integrally formed, with the first transparent layer in immediate contact with the light diffusion layer, and the second transparent layer in immediate contact with the light diffusion layer, and the first transparent layer comprises a plurality of conical frustum protrusions at outer surface thereof that is farthest from the second transparent layer, the second transparent layer comprises a plurality of micro depressions at an outer surface thereof that is farthest from the first transparent layer, each micro depression has at least three side surfaces connected to each other, and a transverse width of each side surface increases along a direction away from the light diffusion layer.   
   
   
       2 . The optical plate as claimed in  claim 1 , wherein a thickness of each of the light diffusion layer, the first transparent layer, and the second transparent layer is greater than or equal to 0.35 millimeters. 
   
   
       3 . The optical plate as claimed in  claim 2 , wherein a combined thickness of the light diffusion layer, the first transparent layer, and the second transparent layer is in the range from about 1.05 millimeters to about 6 millimeters. 
   
   
       4 . The optical plate as claimed in  claim 1 , wherein each of the first transparent layer and the second transparent layer is made of material selected from the group consisting of polyacrylic acid, polycarbonate, methylmethacrylate and styrene copolymer, polystyrene, polymethyl methacrylate, and any combination thereof. 
   
   
       5 . The optical plate as claimed in  claim 1 , wherein a pitch between two adjacent conical frustum protrusions is in the range from about 0.025 millimeters to about 1.5 millimeters. 
   
   
       6 . The optical plate as claimed in  claim 5 , wherein a maximum radius of an inmost end of each conical frustum protrusion is in the range from about 6.25 microns to about 0.75 millimeters. 
   
   
       7 . The optical plate as claimed in  claim 6 , wherein the micro depressions are arranged in a regular array at the outer surface of the second transparent layer, and are separate from one another. 
   
   
       8 . The optical plate as claimed in  claim 1 , wherein the micro depressions are shaped in a form selected from the group consisting of four-sided pyramidal depressions, frustums of four-sided pyramidal depressions, four-sided pyramid-like depressions, and frustums of four-sided pyramid-like depressions. 
   
   
       9 . The optical plate as claimed in  claim 8 , wherein for each four-sided pyramidal depression and each frustum of a four-sided pyramidal depression, a first pair of opposite sides defines a first dihedral angle, a second pair of opposite sides defines a second dihedral angle, and each of the first and second dihedral angles is in the range from about 60 degrees to about 120 degrees. 
   
   
       10 . The optical plate as claimed in  claim 8 , wherein each of the frustums of four-sided depressions comprises four side surfaces, and each of the side surfaces is an isosceles trapezoid. 
   
   
       11 . The optical plate as claimed in  claim 8 , wherein each of the four-sided pyramid-like depressions comprises four side surfaces, the four side surfaces comprise a pair of first opposite side surfaces parallel to a first direction, each of said pair of first opposite side surfaces being isosceles triangles, and a pair of second opposite side surfaces parallel to a second direction, each of said pair of second opposite side surfaces being isosceles trapezoids, and the first direction is perpendicular to the second direction. 
   
   
       12 . The optical plate as claimed in  claim 8 , wherein each of the frustums of four-sided pyramid-like depressions comprises four side surfaces and an inmost surface, each of the side surfaces is an isosceles trapezoid, each of a pair of first opposite side surfaces is larger than each of a pair of second opposite side surfaces, and the inmost surface is rectangular. 
   
   
       13 . The optical plate as claimed in  claim 1 , wherein at least one of the following interfaces is planar: an interface between the first transparent layer and the light diffusion layer, and an interface between the second transparent layer and the light diffusion layer. 
   
   
       14 . The optical plate as claimed in  claim 1 , wherein at least one of the following interfaces is nonplanar: an interface between the light diffusion layer and the first transparent layer, and an interface between the light diffusion layer and the second transparent layer. 
   
   
       15 . The optical plate as claimed in  claim 14 , wherein the interface between the light diffusion layer and the first transparent layer is defined by a plurality of protrusions of the first transparent layer interlocked in a corresponding plurality of depressions of the light diffusion layer. 
   
   
       16 . The optical plate as claimed in  claim 1 , wherein a material of the transparent matrix resin of the light diffusion layer is selected from the group consisting of polyacrylic acid, polycarbonate, polystyrene, polymethyl methacrylate, methylmethacrylate and styrene copolymer, and any suitable combination thereof. 
   
   
       17 . The optical plate as claimed in  claim 1 , wherein a material of the diffusion particles is selected from the group consisting of titanium dioxide, silicon dioxide, acrylic resin, and any combination thereof. 
   
   
       18 . A direct type backlight module, comprising:
 a housing;   a plurality of light sources disposed on or above a base of the housing; and   an optical plate disposed above the light sources at a top of the housing, the optical plate comprising:
 a first transparent layer; 
 a second transparent layer; and 
 a light diffusion layer between the first transparent layer and the second transparent layer, the light diffusion layer including a transparent matrix resin and a plurality of diffusion particles dispersed in the transparent matrix resin, wherein the first transparent layer, the light diffusion layer, and the second transparent layer are integrally formed, with the first transparent layer in immediate contact with the light diffusion layer, and the second transparent layer in immediate contact with the light diffusion layer, and the first transparent layer defines a plurality of conical frustum protrusions at outer surface thereof that is farthest from the second transparent layer, the second transparent layer defines a plurality of micro depressions at an outer surface thereof that is farthest from the first transparent layer, each micro depression has at least three side surfaces connected to each other, and a transverse width of each side surface increases along a direction away from the light diffusion layer. 
   
   
   
       19 . The direct type backlight module as claimed in  claim 18 , wherein a selected one of the first transparent layer and the second transparent layer of the optical plate is arranged to face the light sources. 
   
   
       20 . An optical plate, comprising:
 a first transparent layer;   a second transparent layer; and   a light diffusion layer between the first transparent layer and the second transparent layer, the light diffusion layer including a transparent matrix resin and a plurality of diffusion particles substantially uniformly distributed in the transparent matrix resin, wherein the first transparent layer, the light diffusion layer, and the second transparent layer are integrally formed, with the first transparent layer gaplessly in contact with the light diffusion layer, and the second transparent layer gaplessly in contact with the light diffusion layer, and the first transparent layer defines a plurality of conical frustum protrusions at outer surface thereof that is farthest from the second transparent layer, the second transparent layer defines a plurality of micro depressions at an outer surface thereof that is farthest from the first transparent layer, each micro depression has at least three side surfaces connected to each other, and a transverse width of each side surface increases along a direction away from the first transparent layer.